Express 156 as the product of primes.

Write a quadratic polynomial, sum of whose zeroes is 2 and product is -8.

On comparing the ratios of the coefficients, find out whether the pair of equations x – 2y =0 and 3x + 4y -20 =0 is consistent or inconsistent.

If a and b are co-prime numbers, then find the HCF (a, b).